Bulldozer frame with arm stress equalizer and/or limiter

ABSTRACT

Stress reducer in tiltable, diagonal strut braced, bulldozer blade mountings, comprising an intervening link having horizontally spaced apart portions of the link proper universally connected to the inner end of different ones of the diagonal struts, and having a prolongation to the link proper rendering the latter swingable toward and from the bulldozer blade. The prolongation is horizontally disposed, is at one end of the link proper, and extends diagonally forwardly away from the struts and the one end of the link proper. Although not symmetrical because of the offset brace connection to the blade, the geometry selected nevertheless insures equalization of side-load-imposed stress in the so-called push arms provided for mounting the blade, and further insures limitation of stress in the push arms when, under the special circumstance of an imposed side load condition and a tilted blade condition, the tilt induced stress then tends to be additively superimposed in one of the already side-stressed push arms.

United States Patent Kolinger [451 Apr. 18, 1972 [72] lnventor: Kenneth J. Kolinger, Riverside, ll]. [73] Assignee: International Harvester Company,

Chicago, Ill.

[22] Filed: Oct. 30, 1970 [21] Appl. No.2 85,523

[52] U.S. Cl ..172/803 [51 Int. Cl. ..C02f 3/76 [5 8] Field of Search ..172/801, 803-809, 172/802 [56] References Cited UNITED STATES PATENTS 3,503,457 3/1970 Smith et a1 172/803 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Stephen C. Pellegrino Attorney-Floyd B. Harman [57] ABSTRACT Stress reducer in tiltable, diagonal strut braced, bulldozer blade mountings, comprising an intervening link having horizontally spaced apart portions of the link proper univer' sally connected to the inner end of different ones of the diagonal struts, and having a prolongation to the link proper rendering the latter swingable toward and from the bulldozer blade. The prolongation is horizontally disposed, is at one end of the link proper, and extends diagonally forwardly away from the struts and the one end of the link proper. Although not symmetrical because of the offset brace connection to the blade, the geometry selected nevertheless insures equalization of side-load-imposed stress in the so-called push arms pro vided for mounting the blade, and further insures limitation of stress in the push arms when, under the special circumstance of an imposed side load condition and a tilted blade condition, the tilt induced stress then tends to be additively superimposed in one of the already side-stressed push arms.

9 Claims, 5 Drawing Figures BULLDOZER FRAME WITH ARM STRESS EQUALIZER AND/OR LIMITER overstresses that might otherwise be expected to be set up in the mounting when the blade is side loaded in its tilt and un-.

tilted positions. The application particularly relates to a diagonal strut in the mounting and its means of connection between the blade and a push arm, such means of connection being characterized by non-symmetrical geometry to the longitudinal center line of the mounting.

Full appreciation has not heretofore been given .to employing non-symmetrical geometry in a design for reducing stresses set up in bulldozer blade mountings. Such stresses arise from factors external and internal, such as tilting the blade in operation, or encountering side loads in operation, or other things, arising singly or as combined stress causing factors.

The way the stressing manifests itself, among other ways, is by placing the push arms in bending. And the way each push arm strains under the resulting bending force is to bow outwardly or inwardly between its ends, i.e., deflect so as to .be horizontally outwardly convex or horizontally inwardly convex.

Hitherto, stress relief arrangements for bulldozer frames have generally been arranged symmetrically, or essentially so, in the geometry of their mechanism. Symmetry in itself, however, does not always overcome the drawbacks, nor necessarily equalize or limit some of the critical stresses. And such a mirror image design has the further drawback of duplicating parts in the mechanism, i.e., duplicating either all or substantially all of the stress relieving parts on opposite sides of the longitudinal center line of the bulldozer frame.

My invention with the utilization of a particular non-symmetrical geometry materially reduces or substantially eliminates the foregoing drawbacks, as will now be explained in detail. Features, objects, and advantages will either be specifically ppinted out or become apparent when, for a better understanding of my invention, reference is made to the following description, taken in conjunction with the accompanying drawings which show a preferred embodiment thereof and in which:

FIG. I is a showing in side elevation of a crawler bulldozer embodying the invention, as viewed from the right side and with only the front portion thereof appearing;

FIG. 2 is a top plan view of the front mounted blade and the bulldozer frame for mounting same;

FIG. 3 is a rear elevational view taken along the section line III-Ill F FIG. 2;

FIG. 4 is a showing similar to FIG. 1, but with the bulldozer frame arranged tilted and with the stress limiter effective; and

FIG. 5 is a view similar to FIG. 2, but presented as a vectorial diagram.

In a bulldozer tiltable blade mounting having an offset brace connection to the blade so as to embody the improved nonsymmetrical geometry according to my invention, a frame moves up and down with a bulldozer blade 12 mounted thereon to raise and lower the latter. The blade 12 is independently movable on the frame into different pitched positions such as the broken line position 12a to change the suction angle (FIG. 1), and is movable by the frame to different tilted positions, such as the one appearing in FIG. 4.

The geometry of blade tilt will serve as background interest to the reader at this point. In known bulldozer frames, tilting the blade induces bending forces in the push anns, both of which tend to bow outwardly under the strain. This tendency is explained in another specification, U.S. Pat. No. 3,452,828,

- the blade 12 adjacent its upper edge.

More particularly in FIGS. 1 and 2, a crawler bulldozer 14 constituting an outside arm bulldozer includes a tractor 140 which carries left and right trunnions 16 on the outside of, and generally adjacent the rear portions of, the left and right crawler tracks 18.

The trunnions 16 form ball type universal joints with the rear ends of longitudinally extending left and right push arms 20 and 22 included in the frame 10. The frame further includes left and right diagonal'braces or struts 24 and 26 (FIG. 2) universally connected by ball joints 28 to an intermediate, inner side portion of the corresponding left and right push anns 20 and22.

The frame 10 further includes left and right tilt cylinders 30 and 32 connected by pivot pins and brackets 34 to the tops of the push arms and connected by ball joints 36 to the back of Means is provided for raising and lowering the bull-d'ozer frame 10, and includes an appropriate lift frame 38 (FIG. 1) carried by the tractor 14.

Illustrative of one such means is a pair of identical hoist cylinders 40 and 42, the one adjacent the right side of the bulldozer being the only one described, in the interest of brevity. A yoke 44 is joumaled in one end of a gimbal tube, not shown, carried by the frame 38 for rotation at 46. The yoke 44 supports the cylinder 42 for universal movement and includes a gimbal cap in the connection to the cylinder.-

Although hoist cables are equally adapted to raise and lower the blade 12, it is the cylinders 40 and 42 which are shown for the purpose, connected at their rod ends to the blade by means of universal joints 48 to prevent binding. Blade lift control and gimbaling are explained in another specification, U.S. Pat. No. 3,422,729, which is owned by the same assignee and the disclosure of which is incorporated in entirety herein by reference.

A universal action joint between each of the push arms and the blade 12 is provided by crossed pins in each joint consisting of a horizontal pin 50, parallel to the length of the athwartwise extending blade 12, and a vertical pin 52. Generally adjacent the corners of the frame 10 so formed, the diagonal struts 24 and 26 extend from the ball joints 28 inwardly and forwardly from the inner sides of the push arms, and means of securement to the blade is provided at the inner ends of the which is owned by the same assignee and the disclosure of struts, described as follows.

SECUREMENT FIGS. 1, 2, and 3 For purposes of securing the struts, a link-supporting, single swing connection 54defining a vertical axis 56 is secured in non-symmetrical disposition to the blade at a distance which is both forwardly and transversely offset from both of, and confined at said distance to the same side of both of, the inner ends ofthe diagonal struts 24 and 26. The struts have a one piece, common connecting link proper 58. The common link is arranged with separated portions of the connecting link proper having ball joints 60 forming universal connections to different ones of the diagonal struts at their inner end, and further arranged with an obtusely diagonal integral prolongation 62 at one end of the connecting link proper connected to the single swing connection 54 for the common link. Vertically spaced apart lugs 64 support the swing connection 54 on the blade to fix the axis 56 relative thereto.

HEIGHT FIG. 1

Conjoint extension and conjoint foreshortening of the lift cylinders 40 and 42 change the elevation of the bulldozer frame 10 and the blade 12 thereon by pivoting the former up and down about the athwartwise. horizontal axis interconnecting the trunnions 16 of the crawler bulldozer 14.

PITCH FIGS. 1 and 2 Conjoint foreshortening and conjoint extension of the tilt cylinders 30 and 32 pitch the blade 12 between its solid line position and broken line position 12a, the latter position being frontwardly pitched and providing an increased suction angle for ease in handling hard material, for example.

The horizontal pins 50 and the ball joints 60 are precisely aligned and define in common an athwartwise blade pitch axis 66 (FIG. 2). Such precise alignment occurs when the link proper 58 is parallel to the horizontal blade 12 and coaxial with the axis 66.

TILT FIGS. 2 and 4 When a first of the tilt cylinders remains at constant length while the other acts, as by foreshortening, or when the first named cylinder acts in the opposite direction, as by extending while the other is foreshortening, the blade 12 pivots generally about a longitudinal central axis 68. The result is that one end of the blade, e.g., the right end as shown in FIG. 4 goes down while the left end goes up in conformity with the tilt angle selected. The equivalency is as if the push arms were to have been inwardly deflected, by the increments shown, to the positions 20a and 22a, FIG. 2, forcing the inner ends of the diagonal struts forwardly. About its fixed swing connection 54, the link proper 58 moves generally toward the blade 12 and skews slightly in a horizontal plane, so as to take the position of advancement as shown by broken lines 58a in FIG. 2 and by solid lines 58in FIG. 4.

The link pivots into only forward angles, and never a rear angle. Inasmuch as there is no solid metal path against which the inner ends of the diagonal struts can react, the give" in the mechanism relieves practically all of the pure-tilt-caused stress, and bending forces are not set up on the inner sides of the push arms at the ball joint connections 28. When the blade 12 is untilted, the link proper 58 and the inner ends of the diagonal struts return from their position of advancement.

Obviously, stress relief accommodated by the guided movement of the connecting link proper 58 is a necessity or else the basic purpose would not be served. In connection therewith, however, novelty is felt to reside in achieving one important design objective hereof, namely, doing so by utilization of non-symmetrical geometry.

Novelty is also felt to reside in two more of the design objectives hereof in connection with non-symmetry. The two are first nonparallelogram action with, and second equalized stress between, the push arms as will be later detailed.

PURE SIDE LOADING FIGURE According to the geometry in FIG. 5, the link proper 58 has a position of static equilibrium. Such position is to the rear of and parallel to a reference line RL interconnecting the point SC of swing connection 54 and the reference point RP of intersection between the convergent axes of the diagonal struts, when extended, from the inner ends of such struts, not shown. Depending upon the link anchoring mechanism on the blade, the link is readily afforded a shifting point SC of swing connection to the blade. In the actual showing hereof, which is a simplified showing, the link swings on a fixed point SC having a fixed axis 56.

The mathematics have been and can be readily developed, by taking moments about the point SC of swing connection, showing the advantage of the equilibrium condition. Specifically, consider a thrust on the blade 12 from either side, for instance, the one represented by the vector S on the right side, resulting in a stress represented by the vector L in push arm and a stress represented by the vector R in push arm 22. The referred to advantage of the condition is that vectors L and R will be equal and will impart equal bending stress in the push arms whenever the condition of pure side loading satisfies the simple equation:

Tan A 2 e/b The angle A is the same on each side of the longitudinal center line 68 and is the included angle between the diagonal strut at that side and the link proper 58. The eccentricity is designated e occurring as the shortest distance between the reference point RP and the centerline of the link proper 58. The centerto-center distance between the strut ball joints 70 is designated b. The pitch axis is indicated at 66 and the athwartwise, horizontal frame trunnion axis is indicated at 70.

COMBINED TILT AND SIDE STRESS FIGURE 2 FIG. 2 can aid in visualizing the vectorial arrangement but not the structural arrangement of prior art frames lacking the present stress equalization and/or limitation. A side load represented by the vector S in a prior art frame vector diagram causes compressive stress in the diagonal strut 24. The push arm reacts by outward bowing to the strut compressive stress, which stress is represented by a vector Y. The vector Y is superimposed additively in the strut to the stress of tilt therein represented by the existing vector Z, the combination of the two of which vectors causes reaction by the push arm through the ball joint in its broken line position 28a so as to overstress the prior art push arm in bending.

By way of comparison however, tilt stress on which side load stress is superimposed does not additively combine as such a bending force in applicant's push arm 20 when tilted into its dotted line position indicated at 20a. All or most of the tilt stress which would generate as compression as represented by the vector Z in the prior art frame considered dissipates in thin air in applicant as applicants link proper freely swings to its broken line position 58a of accommodation. Although the condition of accommodation to combined side and tilt load does not exactly equalize the bending between the two push arms 20 and 22 of applicant, such a condition is approximated. In theory, the ideal condition of stress equalization is approached as the distance between the reference point RP, on the center line 68, and the one-way offset point of swing connection SC is increased. Thus, the illustrated vector diagram of FIG. 5 more nearly approaches the ideal situation of stress equalization during combined tilt and side load because of the comparatively greater distance apart illustrated between the points RP and SC.

Applicants first mentioned design objective of asymmetrical geometry proves itself in the basic simplicity of providing the single offset swing connection 54 for the link. It is an important feature of my invention that the link is a single link, amounting essentially to one additional part which, when added to an unrelieved prior art frame, converts same to a stress relieved frame.

Also, applicants two further design objectives with the nonsymmetrical single swing point arrangement are now apparent from the foregoing. First, the non-symmetrically anchored link proper 58 prevents parallelogram action of the push arms 20 and 22 about the trunnions 16. The equal loading vectors L and R prevent give in the frame, and the push arms strain in bending to actively resist the pure side load represented by the vector S. Second, the non-symmetrically anchored link proper 58 establishes the illustrated position of static equilibrium, and the load is equally distributed. Thus the push arms 20 and 22 share the pure side load represented by the vector S so that neither push arm is strained in excess of the other.

The mathematics is equally readily developed to show load equalization between the push arms when the thrust represented by the vector S is applied to the blade 12 at the opposite side from the side of application illustrated in FIG. 5.

Other than for the essentiality of ball type joints carried at each end, or at least at the inner end, the diagonal struts 24 and 26 are standard bipartite construction, adjustable to a fixed length by the usual screw threaded connection provided between the end parts of the strut.

The struts are used for alignment purposes during initial installation of the frame, made while the lengthwise-mounted blade 12 is horizontal. The struts 24 and 26 are foreshortened to draw the link proper 58 away from the blade until the true geometry is achieved for the static equilibrium desired, with the link proper arranged parallel in its solid line position shown in FIG. 2. In this manner, the controlling condition that Tan A 2 e/b is satisfied at the start of operation. Then with pure side loading, the link proper 58 stays in the solid line position, which is its rearmost position of operation. During tilt and untilt of the blade, the link proper 58 swings from its geometrically established rear limit as represented by the solid line position 58 t0 and fro relative to the blade 12 for tilt stress reduction.

Variations within the spirit and scope of the invention described are equally comprehended by the foregoing description.

What is claimed is:

1. In a dozer blade frame in which blade push arms are provided, having mounting means of connection for tiltably mounting the blade thereon, having diagonal struts extending from the push arm inner sides toward the blade, and having means to effect tilting of the blade on the blade mounting means relative to the push arms, the improvement in stress equalization means for the arms, having:

a link supporting, single swing connection on the blade, secured in non-symmetrical disposition thereto at a distance which is both forwardly and transversely offset from both of, and confined at a distance to the same side of both of, the inner ends of the diagonal struts; and

a one piece, common connecting link proper, arranged with separated portions of the connecting link proper universally connected to different ones of the diagonal struts at their inner end, and arranged with a prolongation to the connecting link proper connected to the single swing connection for the common link.

2. The invention of claim 1, characterized by the prolongation being integral with the connecting link proper.

3. The invention of claim 2, further characterized-by the prolongation being obtusely diagonal to the link proper.

4. The invention of claim 1, characterized by the connecting link proper being swingable to a position parallel to a reference line interconnecting the point of swing connection and the point of intersection between the convergent axes of the diagonal struts when extended from the inner end.

5. The invention of claim 4, characterized by the parallel position being a position of static equilibrium of the link proper, equalizing the respective bending forces set up in the push arms from the applied stress of pure side loading.

6. The invention of claim 1, characterized by the mounting means of connection defining a blade pitch axis passing at least within the near vicinity of the universal connections on portions aforesaid of the link proper.

7. The invention of claim 1, in combination with the blade, blade mounting means, push arms, and means to effect tilting of the blade on the blade mounting means relative to the push arms, said means characterized by:

tilt strut means at each side of the frame and each extending upwardly between the top of the push arm at that side and the blade, at least one being an hydraulic tilt strut cylinder extensible and foreshortenable solely to tilt the blade on the mounting means.

8. The invention of claim 7, characterized by two of the hydraulic tilt strut cylinders, hydraulically simultaneously foreshortenable and simultaneously extensible to pitch the blade, and hydraulically simultaneously oppositely actuable to tilt the blade.

9. In the initial installation of a bulldozer frame composed of a horizontally installed lengthwise mounted blade presenting a fixed swing connection, symmetrically disposed blade push arms having mounting means of connection for tiltably mounting the blade thereon including universally connected push ends on the arms, adjustable diagonal struts disposed one at each inner side of the push arm end at that side and extending toward the blade, and a one piece common equalizing connecting link arranged with the link proper universally connected to different ones of the diagonal struts at their inner end, and arranged with a prolongation to the link proper connected to the swing connection fixed on said blade, said swing connection consisting of a single diagonally forwardly offset swing connection point for the link, a frame alignment method characterized by the steps of:

foreshortening one strut for retracting the link proper from the blade; and, simultaneously,

foreshortening the other strut similarly whereby to coordinate retraction of the link proper, all in the interest of swinging the link proper parallel to a reference line interconnecting the tpoint of swing connection and the oint of intersection be een the convergent axes of the iagonal struts when extended from their inner ends. 

1. In a dozer blade frame in which blade push arms are provided, having mounting means of connection for tiltably mounting the blade thereon, having diagonal struts extending from the push arm inner sides toward the blade, and having means to effect tilting of the blade on the blade mounting means relative to the push arms, the improvement in stress equalization means for the arms, having: a link supporting, single swing connection on the blade, secured in non-symmetrical disposition thereto at a distance which is both forwardly and transversely offset from both of, and confined at a distance to the same side of both of, the inner ends of the diagonal struts; and a one piece, common connecting link proper, arranged with separated portions of the connecting link proper universally connected to different ones of the diagonal struts at their inner end, and arranged with a prolongation to the connecting link proper connected to the single swing connection for the common link.
 2. The invention of claim 1, characterized by the prolongation being integral with the connecting link proper.
 3. The invention of claim 2, further characterized by the prolongation being obtusely diagonal to the link proper.
 4. The invention of claim 1, characterized by the connecting link proper being swingable to a position parallel to a reference line interconnecting the point of swing connection and the point of intersection between the convergent axes of the diagonal struts when extended from the inner end.
 5. The invention of claim 4, characterized by the paraLlel position being a position of static equilibrium of the link proper, equalizing the respective bending forces set up in the push arms from the applied stress of pure side loading.
 6. The invention of claim 1, characterized by the mounting means of connection defining a blade pitch axis passing at least within the near vicinity of the universal connections on portions aforesaid of the link proper.
 7. The invention of claim 1, in combination with the blade, blade mounting means, push arms, and means to effect tilting of the blade on the blade mounting means relative to the push arms, said means characterized by: tilt strut means at each side of the frame and each extending upwardly between the top of the push arm at that side and the blade, at least one being an hydraulic tilt strut cylinder extensible and foreshortenable solely to tilt the blade on the mounting means.
 8. The invention of claim 7, characterized by two of the hydraulic tilt strut cylinders, hydraulically simultaneously foreshortenable and simultaneously extensible to pitch the blade, and hydraulically simultaneously oppositely actuable to tilt the blade.
 9. In the initial installation of a bulldozer frame composed of a horizontally installed lengthwise mounted blade presenting a fixed swing connection, symmetrically disposed blade push arms having mounting means of connection for tiltably mounting the blade thereon including universally connected push ends on the arms, adjustable diagonal struts disposed one at each inner side of the push arm end at that side and extending toward the blade, and a one piece common equalizing connecting link arranged with the link proper universally connected to different ones of the diagonal struts at their inner end, and arranged with a prolongation to the link proper connected to the swing connection fixed on said blade, said swing connection consisting of a single diagonally forwardly offset swing connection point for the link, a frame alignment method characterized by the steps of: foreshortening one strut for retracting the link proper from the blade; and, simultaneously, foreshortening the other strut similarly whereby to coordinate retraction of the link proper, all in the interest of swinging the link proper parallel to a reference line interconnecting the point of swing connection and the point of intersection between the convergent axes of the diagonal struts when extended from their inner ends. 